Cessna 340 Page 1 of 14 Volume 34 • Number 2 • February 2004 Cessna 340 A fast, pressurized cabin-class twin that’s an excellent step-up from a Avionics Report high performance single. Used Aircraft Guide Maintenance Matters Accessories Although airplanes are often sold as Misc. business and transportation tools, the reality of ownership falls short of the ideal. They either lack the range, the carrying capacity or the ability to deal with real-world weather, thus an airline or a charter outfit gets the call. Still, there are plenty of pilot/businessmen who couldn’t function without an airplane. These owners typically start with single- The Cessna 340 is a standout thanks to engine airplanes and quickly outgrow payload/fuel flexibility and near 200-knot cruise them for the reasons stated above. A speeds. Pressurization is an added plus. serious business airplane needs a decent cabin, credible speed and the ability to hack it when there’s ice or thunder in the forecast. Pressurization is nice since the clients don’t want to spend several hours with a plastic hose stuck up their noses. Enter the Cessna 340. Owners looking to step-up from a high-performance single will inevitably make a pass or two through the 340 classified section. And well they should. Although not without its shortcomings—most notably certain loading limitations and an overly complex fuel system—the 340 is nevertheless an impressive, flexible and capable airplane that meets the business mission well and can do double duty as a family airplane. Model History The 340 owes its existence to the boom days of general aviation during the late 1960s and early 1970s. It appeared in 1972 as a lower-cost alternative to the Cessna 414, which had arrived in 1970. In those days, the twin market was still a work in progress and it was stratified. At the entry level, you had Twin Comanches, Apaches, Aztecs, Baron and the Cessna 310. At the upper end, the ritzy cabin-class Cessna 421, Beech Duke and Piper Navajo met the needs of well-heeled owners who could afford megabucks for an airplane. The 340 found its niche in between; a cabin class, yes, but a modest one with an affordable price tag. Although it carries a 300-series number, the 340 and 414 are similar, sharing the same wing, flaps, ailerons, landing gear and engines. Like the 414 and other cabin twins, the 340 has an air-stair door, thus you don’t need a ladder to get into it, as some have jokingly complained about the long-legged Cessna 310. With the same engines as the 414 but at a lower weight, the 340 is faster than the 414 on the same fuel burn. But there’s no free lunch; it gives up some payload to the higher-priced model. Engines installed in 340s from 1972 through 1975 were Continental TSIO-520Ks, which produce 285 HP at 33 inches manifold pressure from sea level to 16,000 feet. However, most of the K engines in early 340s have been converted to Js or Ns. The TSIO-520J engine, used on early 414s, produces 310 HP at 36 inches manifold pressure. The N engine, installed on later 414s and 340s (the N-engine airplanes are called 340As), http://www.aviationconsumer.com/archives/34_2/usedaircraftguide/5317-1.html 2/15/2006 Cessna 340 Page 2 of 14 produces 310 HP at 38 inches. The major difference between the K engine and the J and N variants is that the latter are equipped with intercoolers which wash the heat out of the turbocharged induction air as it flows on its way to the cylinders. This yields better power and efficiency without stressing the jugs, something that’s good for longevity. The N engines produce their rated 310 HP up to 20,000 feet and provide higher cruise speeds and better climb and single-engine performance. Three-blade McCauley propellers, formerly an option, also became standard equipment in 1976; earlier 340s came with two-blade McCauleys. These airplanes are prized for being all-weather machines but certification for flight into known icing conditions, when properly equipped, came only in 1977. The following year, a maximum ramp weight of 6025 pounds was approved and max weight for takeoff and landing was set at 5990 pounds for the 340A, compared with 5975 pounds for the 340. The last significant change in the line came in 1979, with the switch to TSIO-520NB engines (the B denotes a heavier crankshaft). Subsequent modification of cylinders, valve lifters and piston pins by Continental increased TBO of the NB engines from 1400 to 1600 hours in 1983. But Cessna didn’t build any 340As (or much of anything else) that year and after putting together a scant 17 of the airplanes in 1984, production was terminated for good, with a total of about 1297 aircraft made. Some 923 are still registered. Systems As basic systems go, the 340 is unique on two accounts. One, it has pressurization and two, it has a complex fuel system that isn’t something the novice should confront without training. The pressurization system is the same as those found in Cessna’s 400-series twins, with a maximum differential of 4.2 PSI providing an 8000-foot cabin up to 20,000 feet. Above that, the cabin climbs with the airplane. Cessna offered an automatic pressurization control, which activates and deactivates while climbing or descending through 8000 feet. A few airplanes have it but more buyers opted for the variable-control system, which allows the pilot to program cabin altitude and rate of climb. The variable system maintains a sea-level cabin up to 9000 feet, then delivers the pilot- selected cabin altitude until a 4.2 PSI differential is reached. As pressurization goes, the 340’s is relatively easy, requiring just a quick check and set for each flight. The pilot merely dials in field elevation plus 500 feet before takeoff and landing and selects desired cruise cabin altitude on initial climb. The rest is simply monitoring the system to make sure it’s delivering the commanded numbers. While the pressurization is easy, the same can’t be said for the fuel system. Start with the tip tanks—which are the mains in this airplane. They hold 100 usable gallons. Add up to four auxiliary wing tanks, two holding 40 gallons, the other two holding 23 gallons. Throw in locker tanks, which add another 40 gallons. That’s up to 203 gallons in tanks peppered throughout the length of the wings. Where things get tricky for the uninitiated is which tank to use when. Use the mains, alone, for takeoff and landing. The engines feed directly from the auxiliary tanks, but fuel in the lockers has to be transferred to the mains. Of course, you have to make room in the mains first, otherwise you’ll vent the pumped fuel over the side. And if you have only one locker tank (which many 340s do have), remember to use crossfeed; dump all 120 pounds from a locker into one tip tank, and the imbalance will be enough to upset even your autopilot. Unfortunately, Cessna never got around to simplifying the fuel systems in its 300-series twins (Crusader excepted) as it did in most of the 400s. And for whatever reason, Cessna chose to designate the tip tanks “main,” just as they did on the 310. This can, and has, caused some problems. Ramp attendants have filled the wrong tanks (“Just top off the mains....”) and pilots, particularly transitioning pilots, have switched to the aux tanks thinking they were drawing from the tips, and vice versa. Despite this Byzantine fuel system design, the 340 hasn’t suffered an inordinate number of fuel-related accidents. However, what we don’t know is how many inadvertent inflight stoppages or unscheduled landings have occurred because of confusion over the fuel system. http://www.aviationconsumer.com/archives/34_2/usedaircraftguide/5317-1.html 2/15/2006 Cessna 340 Page 3 of 14 Performance The 340 is definitely a high flyer, with a service ceiling of nearly 30,000 feet. But most owners wisely operate in the high teens to mid-20s, where the airplane can be expected to true between 190 and 205 knots on about 30 gallons per hour at 65 percent power and 200 to 217 knots on 32 to 34 GPH using 75 percent power. Rate of climb at sea level is a respectable 1650 FPM, but climb performance tapers above 20,000 feet to a dawdling 300 to 400 FPM in the mid-20s. Not bad as twins go, but certainly no turboprop, either. The 340’s claimed single-engine rate of climb is 315 FPM, better than the 414 (290 FPM), Beech P58 Baron (270) and the Piper 601P (240) and 602P (302) Aerostars. In its class, the 340 is bettered in climb only by its lighter, centerline-thrust stablemate, the pressurized Skymaster, which climbs 375 FPM on one engine. Single-engine minimum control speed is 82 knots. Stall speeds are 79 knots, clean, and 71 knots in landing configuration. Not all twins of the 340s days have accelerate-stop and accelerate-go performance tables but, to Cessna’s credit, the 340 does. Under standard conditions, a 340 that loses an engine at lift-off speed (91 knots) can be brought to a full stop within 3000 feet of brake release. The POH also indicates that should a pilot decide to fly after losing one on lift-off, the airplane will clear a 50-foot obstacle after traveling less than 4000 feet over the ground after brake release.